Computer telephony integration products are well-known and widely used to provide personal as well as corporate telephone services. The use of computer telephony integration products permits enhanced dialling and call handling features. A shortcoming of such products is that those features are enabled outside the Public Switched Telephone Network (PSTN). Consequently, call completions effected using such products often use redundant circuits in the PSTN. Efficiency is therefore sacrificed. A further disadvantage of such products is that they have no access to the signaling network which controls the PSTN. Consequently, such products are incapable of determining the status of a remote user line or querying PSTN nodes to obtain information useful in call setup or call direction. There therefore exists a need for computer telephony integration products that are more completely integrated with the PSTN.
Another commonly used system in the PSTN are call centers which offer customer support, help lines, or the like. Such centers typically use an out-dialer to set up calls to a predetermined list or queue of numbers which are to be called. To improve performance, algorithms have been developed to predict when an agent will become available to take a call, and calls are placed in advance of agent availability. If a number dialled is not answered, the number is moved to a bottom of the queue and retried when it has advanced again to the top of the queue. Due to the fact that such dialers have no access to the PSTN signaling network, it is difficult or impossible to write algorithms to accurately and consistently determine the reason that any particular call is not answered when dialed. Consequently, calls may be attempted many times over even though there is no probability of reaching the called party. This wastes transport and signaling facilities and ties up resources that could be profitably used by others. There therefore exists a need for better out-dialer facilities for call centers.
In the applicant's co-pending patent application described above, a method and a system for completing voice connections between voice terminals in a Switched Telephone Network (STN) using the flexibility of computer control exercised through a data network independently of voice terminals connected to the network was disclosed. The method and system provide several advantages over prior art methods of completing voice connections. First, it provides all the advantages and flexibility of computer control, including automated dialling from electronic telephone books or directories. It also provides the advantage of sequential calling without disconnection of the calling party so that a plurality of sequential calls may be completed without interrupting the user's voice connection with an originating switching point (SP) in the STN.
The system disclosed in applicant's co-pending application includes a Virtual Switching Point (VSP) which is a physical node in the signaling network of the STN and a virtual node in the transmission network of the STN. The VSP is enabled to receive call request messages from a data network such as a local area network (LAN), a wide area network (WAN), an Intranet or the Internet. The VSP processes the call request which may include more than one called number. A call request is processed by sending a common channel signaling message from the VSP to an SP in a local calling area of the calling party to initiate a voice connection with the calling party. After the connection is established with the calling party, a second common channel signaling message is sent to a switching point in the STN to initiate a connection with the called party. The two connections are the first and second legs to the same call. The voice connections may be local or long distance voice connections.
While this system provides significantly improved functionality over the computer-integrated telephony systems of the prior art, and capitalizes on the inherent switching capability of the PSTN, it does not capitalize on the inherent query capability of a common channel signaling network. In particular, the common channel signaling system, Signaling System 7 (SS7) provides a query signaling capability known as Transaction Capability Application Part (TCAP) signaling. TCAP signaling provides a powerful query tool which may be used by physical nodes in an SS7 network.
There therefore exists a need for call completion systems which use the inherent switching power resident in the PSTN as well as the inherent query capability resident in the common channel signaling network that controls the PSTN.